POJ1990 MooFest——树状数组

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维护两个树状数组，一个记录这个坐标所控制的范围内的奶牛个数，另外一个记录这个坐标所控制范围内的奶牛坐标之和。

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Program POJ1990;//By_PoetshyConst maxn=20000;Vari,n:Longint;p,m,ans:Int64;v,x,a,h:Array[1..maxn]of Int64;Procedure Qsort(l,r:Longint);var i,j,k,temp:Longint;begini:=l;j:=r;k:=v[(i+j)>>1];repeatwhile v[i]<k do inc(i);while v[j]>k do dec(j);if i<=j then begintemp:=x[i];x[i]:=x[j];x[j]:=temp;temp:=v[i];v[i]:=v[j];v[j]:=temp;inc(i);dec(j);end;until i>j;if i<r then Qsort(i,r);if l<j then Qsort(l,j);end;Function Count(i:Longint):Int64;beginCount:=0;while i>0 do begininc(Count,a[i]);dec(i,(i)and(-i));end;end;Function Counth(i:Longint):Int64;beginCounth:=0;while i>0 do begininc(Counth,h[i]);dec(i,(i)and(-i));end;end;Procedure Deal(i:Longint);var j:Longint;beginj:=x[i];while j<=maxn do begininc(a[j]);inc(h[j],x[i]);inc(j,j and(-j));end;end;BEGINreadln(n);for i:=1 to n do readln(v[i],x[i]);Qsort(1,n);for i:=1 to n do beginp:=Count(x[i]);m:=Counth(x[i]);inc(ans,v[i]*(p*x[i]-m));p:=Count(maxn)-p;m:=counth(maxn)-m;inc(ans,v[i]*(m-p*x[i]));Deal(i);end;writeln(ans);END.